Portable Wi-Fi hotspots, powered by 3G, are banned at all the Olympic venues in London. But while that might sound like a hollow threat, this man makes sure it isn't, by sniffing out rogue Wi-Fi networks and shutting them down.

There is, of course, good reason to want to keep portable Wi-Fi hotspots out of the games. At events that increasingly rely on wireless communication —for everything from referee mics through timing devices to wireless cameras—interference could easily get in the way of the smooth running of things. As the saying goes, better to be safe than sorry.